For many years, dental burs have been used for cutting hard tissues—tooth or bone. They are generally made of steel, stainless steel, tungsten carbide and/or diamond grit. There are many bur shapes that are utilized in various specific procedures, such as cavity preparation and creating access points. Over the years, there have been a number of advancements, e.g. high-speed turbines, lasers and microabrasion, but a large majority of dentists still use the traditional hand piece and bur combination for the majority of their clinical work.
Dental cutting or polishing procedures must be performed under a coolant to avoid side effects caused by heating during operation of the cutting instrument. High Speed and Low Speed dental hand pieces have utilized water spray as a cutting fluid for many years. In designing early systems, municipal water system supply lines were simply connected directly to the dental unit. This water was then distributed throughout the dental unit via small diameter tubing water lines leading to the dental hand piece, typically mixed with pressurized air and delivered as a fine spray aimed at the cutting interface between the dental bur and tooth structure. Water irrigation delivered in this manner provided benefit as it continually kept the site cleaner than dry preparation would by physically washing debris from the cutting site. A second benefit of irrigation is that it decreases the negative side effect of heat produced during cutting with fast rotational speeds of dental burs. Unchecked, such negative thermal effects can result in severe and possibly irreversible damage to the dental pulp, and are to be avoided. Therefore, keeping temperatures cool at the cutting interface of the dental bur and tooth structure is desirable.
Infection control in dentistry has increasingly become a concern, and in recent years there has been much concern over the growth of biofilm in small diameter water lines used to deliver water to the cutting site. Small amounts of bacteria are naturally present in municipal water systems. The presence of these bacteria, along with bacterial contamination potentially reintroduced back into the dental unit by retrograde fluid flow can potentially lead to bacterial colonization and biofilm formation in water lines. It has been demonstrated that there is a slower flowing outer column of water present inside small diameter water lines. This slower flowing column near the wall of small diameter lines means that bacterial contamination can remain for longer periods of time and results in proliferation of bacteria, and formation of biofilm that allows colonies of bacteria to firmly attach to the walls of water lines. This unchecked proliferation of the biofilm and colonies then leads to budding off of bacterial colonies by detachment. Once detached, the colonies then migrate downstream and could potentially result in contamination of the water delivered to the cutting site and, ultimately, exposure to the dental patient.
In an effort to address this contamination, dental unit manufacturers developed self-contained dental unit water line irrigation systems (S-CDUWLIS). This type of system, rather than being directly connected to the municipal water supply, utilizes a small bottle to contain water used for irrigation. The bottle is pressurized with compressed air above the water surface. Water is then siphoned away under pressure to allow delivery of the water to the cutting site in the same manner as conventional systems. The main advantage of the self-contained systems, unlike conventional systems is that the bottle can be depressurized, the water purged from the system and discarded, followed by the introduction of cleaning solutions into the bottle. The bottle is then pressurized again and these cleaning solutions distributed throughout the S-CDUWLIS to effectively decrease or eliminate biofilm contamination, thereby disinfecting the irrigation system pathway. Upon completion of this disinfection, the system can be purged of all cleaning solutions, rinsed, and fresh water reintroduced into the system for use. One method used and commercially available from a number of manufacturers is the addition of silver ions via nanoparticles to water. One associated drawback with these preparations is that taste is very unpleasant.
In light of the problems advanced above, there exists a need for a method of use of a dental cutting lubricant for providing physical cleansing of the cutting site, as well as improved cutting efficiency and bacteriostatic action necessary to provide decontamination maintenance of dental water lines.